Fastener being pressable into a metal sheet in a way safe against rotation and pressing out

ABSTRACT

A fastener ( 10 ) being pressable into a metal sheet in a way safe against rotation and pressing out having a head ( 12 ), the side of which after insertion facing the metal sheet is having radially positioned ridges ( 22 ), which, when setting the fastener ( 10 ), are pressed into the metal sheet, wherein a cylindrical thread-carrier ( 14 ) is positioned in the centre of said ridges ( 22 ) projecting through the metal sheet beyond the other side of the metal sheet and which in the vicinity of the side of the head ( 12 ) facing the metal sheet in the set state is having a surrounding annular recess ( 20 ) into which the material of the metal sheet displaced during the setting can be pressed.

[0001] The present invention relates to a fastener being pressable intoa metal sheet in a way safe against rotation and pressing out, having ahead or ring the side of which after insertion facing the metal sheet ishaving radially positioned ridges, which, when setting the fastener, arepressed into the metal sheet, wherein a cylindrical thread-carrier ispositioned in the centre of said ridges projecting through the metalsheet beyond the other side of the metal sheet and which in the vicinityof the side of the head or ring facing the metal sheet in the set stateis having an annular recess into which the material of the metal sheetdisplaced during the setting can be pressed.

[0002] Such fasteners can be performed as bolts (having a shaft with anexterior thread) as well as nuts (having a through bore with an interiorthread). A corresponding fastener for example is known from WO 94/01688.

[0003] Similar constructions for example are known from the DE 44 10 475A1, DE 195 35 537 A1 and WO 98/51934.

[0004] In all these known fasteners, the problem is existing that thesecannot anymore be used with a thickness of the metal sheet about orbelow 1 mm or only can be used with a decreased function since thecorresponding safety against rotation and pressing out is not givenanymore.

[0005] Followingly, it is the task to be solved by the present inventionto improve such a fastener in such a way that the fastener can be usedwith metal sheets having a thickness about and even below 1 mm and stillachieving the sufficient safety against rotation and pressing outwithout a special preparation of the opening into which the fastenershould be set being necessary. In solutions as e.g. according to DE 4410 475 A1 or WO 94/01688 around the opening for setting a so-called“collar” of metal sheet has to be formed to achieve a sufficient safetyagainst rotation and pressing out with thinner metal sheets. Thisnecessitates in a disadvantageous way a further procedural step to formthe corresponding “collar”.

[0006] According to the state of art until now one has assumed that anoptimal safety of the fastener against rotation and pressing out isachieved if in the vicinity of the thread-carrier as much space aspossible is provided to receive the metal sheet material. With thinnermetal sheets however not sufficient material of the metal sheet ispresent to fill such spaces. According to the prior art thereforeauxiliary constructions have been used as for example the “collar” fromthe WO 94/01688.

[0007] Contrary to the above, the present invention starts out from thefact that for achieving an optimal safety against rotation and pressingout with thinner metal sheets not too much space for the displacedmaterial of the metal sheet should be provided but only the volume,which by a deliberate deformation (flowing) of the metal sheet can befilled in an optimal way. This shaping into the annular recess isachieved by a flow shaping of the metal sheet material caused by thespecial shape of the ridges.

[0008] According to the invention, the above task is solved by thefeatures that the ridges over a majority of their radial extension arehaving a constant height and width and are in the vicinity of thethread-carrier smoothly merging with the same with an increasing width.

[0009] By such a construction even with very thin metal sheets, asufficient safety against rotation and pressing out of the fastener isachieved.

[0010] For a further improvement of the safety against rotationaccording to the invention it is preferred that the ridges are having abasically rectangular cross-section and their side walls areperpendicular to the side of the head facing the metal sheet. By this,the grip of the ridges in the metal sheet material is further improved.

[0011] To achieve a close contact of the head on the metal sheet andthereby to avoid the formation of gaps it is useful if the ridges in theradial exterior area are tapering off in a flat manner.

[0012] For this purpose, it is of advantage, too, if the ridges in theradial exterior area are tapering off sidewardly in a rounded manner.

[0013] In the following, the invention is more detailedly explained onthe basis of two exemplary embodiments shown in the drawings. In thedrawings show:

[0014]FIG. 1 a side view of a fastener as a bolt according to theinvention;

[0015]FIG. 2 the fastener according to FIG. 1 in a bottom view, whereinthe shaft is cut-off in the plane of the annular recess;

[0016]FIG. 3 a detailed view of the annular recess and the ridges of thefastener according to FIG. 1;

[0017]FIG. 4 a cross-sectional view of one ridge of the fasteneraccording to FIG. 1, wherein the cross-section is across thelongitudinal extension of the ridge;

[0018]FIG. 5 the fastener according to FIG. 1 shortly before being setin the metal sheet;

[0019]FIG. 6 the fastener according to FIG. 1 after setting in the metalsheet;

[0020]FIG. 7 a further embodiment according to the invention beingperformed as a nut, i.e. having an interior thread;

[0021]FIG. 8 the fastener according to FIG. 7 in a bottom view (i.e.seen from the side of the metal sheet), and

[0022]FIG. 9 the fastener according to FIG. 7 partly in section in thestate set in a metal sheet.

[0023]FIG. 1 is showing the fastener according to the invention in theform of a bolt, i.e. having a shaft with an exterior thread. Thefastener 10 according to the invention is having a head 12 and a shaft14 carrying an exterior thread. Between the thread and the head 12 inthe following order there are provided a calibration collar 16, anannular projection 18 and an annular groove 20 having a generallysemi-circular cross-section. On the bottom side of the head 12, which isfacing the metal sheet during the setting of the fastener, there areprovided radially extending ridges 22, which in their radial extensiongenerally having a constant height and which are tapering off in a flatmanner merely in their radial exterior area 21.

[0024] The head 12 is shown partly in cross-section, wherein, on theright side, the corresponding ridge 22, too, is shown in cross-sectionwhile the corresponding ridge 22 on the left side is shown in frontview.

[0025]FIG. 2 is showing the head 12 of the fastener of FIG. 1 in abottom view, wherein the shaft is cut-off in the plane of the annulargroove 20. In FIG. 2, the shape of the ridges 22 is especially wellshown. The ridges 22 extend in a radial direction with a generallyconstant width and merely in the radial exterior area 21 near theexterior edge of the screw head 12 are tapering off in their height in aflat manner and are rounded in their width. In the direction of theshaft 14, the ridges 22 in a rounded manner are merging with the annulargroove 20.

[0026]FIG. 3 is showing a detailed representation of the merger areabetween the head 12 and the thread-carrier 14. In FIG. 3, the taperingoff of the ridge 22 in the exterior area 21 is especially detailedlyshown.

[0027]FIG. 4 is showing a detail, namely, the cross-section of a ridge22, the section being across the radial direction of the head 12. Inthis view, it is extremely well shown how the ridges 22 are shaped intheir cross-section. The ridges 22 generally are having a flatrectangular cross-section and are limited by sidewalls 24 generallyperpendicular to the level of the head 12. Apart from that the surfaceof the ridges 22 facing the metal sheet during the setting generally areeven and parallel to the plane of the head 12.

[0028]FIG. 5 is showing the fastener according to FIG. 1 shortly beforethe insertion into a metal sheet 100 having a corresponding opening 102.The diameter of the opening 102 is chosen such that the fastener can beinserted with the annular projection 18 just without contact.

[0029] In FIG. 6 clearly the indentations 30 are shown caused by thecounter tool during the setting. In the same clear way it is shown howthe annular groove 20 in the area of a ridge 22 has been filledcompletely with the displaced material of the metal sheet (right side inFIG. 6) while on the left side in FIG. 6 it is shown that in the areawhere there is no ridge 22 the annular recess 20 almost completely hasbeen filled with the displaced material of the metal sheet.

[0030] The indentations 30 because of the embodiment of the ridges 22according to the invention and because of the geometry of the annularrecess can be performed in such a flat manner that no substantialdecrease of the stiffness of the metal sheet even with metal sheetshaving a very small thickness is occurring.

[0031]FIG. 7 is showing a further emobdiment of the invention, whereinin this case the invention has been performed with a fastener serving asa nut, i.e. a fastener having an interior thread.

[0032] This further fastener 110 according to the invention is servingas a pressable nut and basically is having a cylindrical shape. In thecentre, the fastener is having a broad surrounding ring 112. In a centreof the cylindrical fastener 110 there is a through-bore which at leastover a part of the height of the fastener 110 is forming athread-carrier 114 with an interior thread. Below the surrounding ring112, the central bore is increased in diameter, which means that in thisarea only a relatively thin annular surrounding ridge 118 is present.

[0033] The fastener 110 according to the invention is meant to beinserted with the ridge 118 first into a hole in a metal sheet 110. Onthe side of the surrounding ring 112 facing the metal sheet 100 in theset state, i.e. on the underside thereof here, too, there are providedridges 122 the shape of which being the same as the shape or the ridges22 in the embodiment according to FIG. 1.

[0034] The shape and the position of the ridges 122 can be more clearlydescribed with reference to FIG. 8. This is showing the fastener of FIG.7 from below. Here, too, the radially extending ridges 122 in theirradial direction are having a basically constant width. Merely in theradially exterior area 122 they are rounded in their width and aretapering off in their height. Apart from that the same representation ofthe cross-section is valid for the ridges 122 as shown for the ridges 22in FIG. 4. They therefore are having a basically flat surface directeddownwardly and being parallel to the level of the ring 112 and sidewallsbasically perpendicular thereto. Merely in the direction of the ring118, i.e. to the interior the ridges 122 in a rounded manner are mergingwith said ring, which means that they are having a rounded increase oftheir width in the radially interior area.

[0035] The bottom side of the ring 112 in the direction to the interiorcan be slightly recessed such that in this area the bottom side of thering 112 not is horizontal but slightly concave.

[0036]FIG. 9 is showing the fastener of FIG. 7 in the set state. Thefastener 110 is pressed into a hole in the metal sheet 100 having acorresponding diameter. In this connection, the hole in the metal sheet100 should have a diameter, which makes it possible to insert thefastener 110 with the surrounding ridge 118 just without contact in thehole 102. During the setting, the surrounding ridge 118 by a suitablecounter tool is pressed to the exterior whereby the metal sheet isdisplaced into the edge between the surrounding ridge 118 and the ring112 and between the corresponding ridges 122. Thereby here, too, acorresponding safety against rotation and pressing out is achieved. Inthis case, too, the shape of the ridges 122 is of fundamental importanceto achieve a complete filling of the space between the surrounding ridge118 and the ring 112 even when setting the fastener according to theinvention in a very thin metal sheet 100.

1. Fastener being pressable into a metal sheet (100) in a way saveagainst rotation and pressing out, having a head (12) or ring (112) theside of which after insertion facing the metal sheet (100) is havingradially positioned ridges (22, 122), which, when setting the fastener,are pressed into the metal sheet (100), wherein a cylindricalthread-carrier (14, 114) is positioned in the centre of said ridges (22,122) projecting through the metal sheet (100) beyond the other side ofthe metal sheet (100) and which in the vicinity of the side of the head(12) or ring (112) facing the metal sheet (100) in the set state ishaving an annular recess (20, 120) into which the material of the metalsheet (100) displaced during the setting can be pressed, characterizedin that the ridges (20, 122) over a majority of their radial extensionare having a constant height and width and are in the vicinity of thethread-carrier (14, 114) smoothly merging with the same with anincreasing width.
 2. Fastener according to claim 1, characterized inthat the ridges (22, 122) are having a generally rectangularcross-section with their side walls (24) perpendicular to the side ofthe head (12) or ring (112) facing the metal sheet (100).
 3. Fasteneraccording to claim 1 or 2, characterized in that the ridges (22, 122) inthe radial exterior region (21, 121) are tapering off in a flat manner.4. Fastener according to any of the claims 1 to 3, characterized in thatthe ridges (22, 122) in the radial exterior region (21, 121) aretapering off in a sidewardly rounded manner.
 5. Fastener according toany of the claims 1 to 4, characterized in that the fastener can be setin the metal sheet (100) having openings (102) without specialadditional shapes like colours or the like.